UK

How many? Ordnance Survey has mapped 6,289 UK islands, mostly in Scotland. The British Isles (including Ireland) has 6,806.

Which should I visit? You can't beat Skye, reckons Nick Crane. "There are sights on Skye you will see nowhere else in Britain," he says. "Up in the north, the road between Staffin and Uig squirms above the 250m contour past the pinnacles and cliffs of Quiraing, with its alien place-names such as The Needle, The Prison and The Table. Over on the west coast, on the moor beyond Talisker, there's a mountain walled with polygonal columns of solidified lava as strange as the Giant's Causeway. Then there are the Black Cuillins, the most ferocious range of peaks in Britain."

How many? 6,852, of which 430 are inhabited. The Japanese archipelago stretches for 1,869 miles, around the same distance as the US east coast.

Which should I visit? We've written about Japan's weird and wonderful islands before. There's Naoshima, home to a growing number of outdoor art projects; the Yaeyama Islands, which look like they've been lifted from the Caribbean; or how about the spooky abandoned island of Gunkanjima, which appeared in Skyfall.

Philippines

How many? 7,641, according to the most recent estimate from the country’s National Mapping and Resource Information Authority. That was an increase on a previous estimate of 7,107. They are clustered into the three major island groups: Luzon, Visayas, and Mindanao.

Which should I visit? Our expert Steve Lunt advises a trip to Palawan. He writes: "Think of ‘The Beach’ with Leo, and you'll know roughly what to expect from these island’s prehistoric charms. Whether selling cars or beaches, ‘pristine’ is chronically over-used – but in Palawan, the superlative often truly applies. Jagged limestone cliffs rise like ossified Gothic cathedrals, towering over misty lagoons; countless white-sand beaches fringe these mysterious islands. Mostly untroubled by humans, wildlife dominates the environment."

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Australia

How many? 8,222, according to official statistics. Most of them (3,747) are in Western Australia, followed by Queensland (1,955), Tasmania (1,000), Northern Territory (887) and South Australia (346). The largest, excluding Tasmania (and Australia itself) is Melville Island, just north of Darwin.

Which should I visit? Kangaroo Island, according to Kate Humble. "It’s renowned for its wildlife and nature reserves, my two loves," she says. "You can hire a bike and explore anywhere on the island, or take one of the many walking trails. It has lots of small farms and artisanal producers selling lavender, sheep’s milk, ice cream and honey. There are magnificent views from the coastline, including sea lions and these amazing rock formations called the Remarkable Rocks. And, unsurprisingly, you’ll see kangaroos everywhere, bouncing around. The island is dotted with lots of lakes and forests filled with koalas and rare birds."

Indonesia

How many? 18,307, according to a 2002 survey by the National Institute of Aeronautics and Space (the CIA World Factbook seems to think it’s 17,508, however, while a more recent survey, by a different agency, put the figure at 13,466).

How many? At least 30,000. The exact number is not known, but Georgian Bay contains the world’s largest freshwater archipelago, known as Thirty Thousand Islands. The Saint Lawrence River, meanwhile, which makes up part of the Canada-US border, contains an archipelago of 1,864. The Canadian Gazetteer Atlas records the names of 1,016 individual islands, along with 129 island groups, of which around 250 are inhabited.

Norway

How many? More than 50,000, stretching from Svalbard, deep inside the Arctic Circle, to Bouvet Island, one of the most remote on Earth, and inhabited only by birds and seals, in the South Atlantic.

Which should I visit? The Lofoten Islands. There are beautiful beaches, like Utakleiv, pictured below, as well as stunning mountains and fjords. And despite its Arctic Circle location, the Gulf Stream means temperatures sometimes reach 20C in summer.

Finland

How many? 179,584, according to its tourist board, including 98,050 on the country’s 188,000 lakes.

Which should I visit? The Åland Islands belong to Finland and are a good bet if you want to escape the Sturm und Drang. Paul Miles, who visited in 2012, wrote: "It was a week of Blyton-esque adventures – outings in our own little motorboat, horse riding along flowery lanes, playing on a sandy beach, kayaking between low, bare skerries, spotting sea eagles and fishing for pike with a local fisherman."

Sweden

How many? 267,570, according to Statistics Sweden’s 2013 Islands in Sweden report. Just 984 are inhabited. The number, curiously, appears to be growing, its 2001 report listed 221,800. Either way, it makes Sweden the world's island capital.